Is there any species that uses no water? (If so, probably microscopic or insect.)

[Steven_Estes]

Is there any species that uses no water? (If so, probably microscopic or insect.)

[naita]

Earth life chemistry is water based. So no, not any species we know.

[Exapno_Mapcase]

The answer to this may not be possible until we understand what the OP means by *using *water.

Purple sulfur bacteria

The purple sulfur bacteria (PSB) are part of a group of Proteobacteria capable of photosynthesis, collectively referred to as purple bacteria. They are anaerobic or microaerophilic, and are often found in stratified water environments including hot springs, stagnant water bodies, as well as microbial mats in intertidal zones.[4] Unlike plants, algae, and cyanobacteria, purple sulfur bacteria do not use water as their reducing agent, and therefore do not produce oxygen. Instead, they can use sulfur in the form of sulfide, or thiosulfate (as well, some species can use H2, Fe2+, or NO2−) as the electron donor in their photosynthetic pathways.[4] The sulfur is oxidized to produce granules of elemental sulfur. This, in turn, may be oxidized to form sulfuric acid.

[Colibri]

Given that protoplasm consists of molecules in an aqueous solution, all cellular life requires water. Dormant viruses don’t contain water, but require living cells to reproduce, so they also require water.

[am77494]

We need more clarification on “uses no water”. Bacteria can survive a ride to the moon and back : exposed to space and the worst dry conditions.

They can survive encapsulated in amber for 30 million years…

https://www.panspermia.org/bacteria.htm

[naita]

@Exapno_Mapcase

The answer to this may not be possible until we understand what the OP means by *using *water.

Purple sulfur bacteria

That’s fascinating. But also only part of their metabolism. Could their body chemistry function without any water produced or consumed by reactions?

[vperry1]

I don’t know if they count, but Tartigrades, or water bears, seem to come close to what you mean.

Cite from Wikipedia: Tardigrades are considered to be able to survive even complete global mass extinction events due to astrophysical events, such as gamma-ray bursts, or large meteorite impacts. Some of them can withstand extremely cold temperatures down to 1 K (−458 °F; −272 °C) (close to absolute zero), while others can withstand extremely hot temperatures up to 420 K (300 °F; 150 °C)[36] for several minutes, pressures about six times greater than those found in the deepest ocean trenches, ionizing radiation at doses hundreds of times higher than the lethal dose for a human, and the vacuum of outer space. They can go without food or water for more than 30 years, drying out to the point where they are 3% or less water, only to rehydrate, forage, and reproduce. Tardigrades that live in harsh conditions undergo an annual process of cyclomorphosis, allowing for survival in sub-zero temperatures.

Photo:

[Riemann]

There are plenty of animals that don’t ever drink, and get their water indirectly. It’s a bit of a grey area - if chicken soup doesn’t count as water, presumably humans could too in principle!

But I suspect that’s not what OP meant. As others have pointed out, all life is based on reactions that can take place only in aqueous solution.

[Velocity]

The bacteria and water bears mentioned in this thread don’t fit the OP’s criteria. They still need and use water. They can survive a very long time without it, but still need it in order to reproduce or spore or grow or whatever.

[septimus]

@vperry1

I don’t know if they count, but Tartigrades, or water bears, seem to come close to what you mean.
…
Photo:

The URL in vperry1’s link can be copied (with "-marks deleted) into the Chrome address bar and an image appears. It can be copied into the ‘src’ of an html ‘img’ tag and the image appears. But I don’t know how to click here at SDMB and get the image to appear directly.

[Riemann]

@septimus

The URL in vperry1’s link can be copied (with "-marks deleted) into the Chrome address bar and an image appears. It can be copied into the ‘src’ of an html ‘img’ tag and the image appears. But I don’t know how to click here at SDMB and get the image to appear directly.

I immersed the tardigrade URL in an isotonic solution and it worked fine.